But again, if that is what the guideline is referring to, why does it say "If you want to emphasize a _word or phrase_". By my reading, it is quite explicitly including single words!
Imagine I capitalised a whole selection of specific words in this sentence for emphasis, how annoying that would be to read. I'll spare you. That is what the guideline is about, not one single instance.
I’m saying that being pedantic on HN is a worse sin than capitalizing a single word. Being technically correct isn’t really relevant to how annoying people think you are being.